Figure 5-40.-A non-isometric line (AB) in an isometricprojection.a NON-ISOMETRIC LINE is a line that is notparallel to any one of the three legs of theisometric axis. It is not a normal line in a normalmulti-view projection of the object.The upperpart of figure 5-40 shows a two-view normal multi-view projection of a block.Though the line AB is parallel to the horizontalplane of projection, it is oblique to both thevertical and the profile planes. It is thereforenot a normal, but an oblique, line in the multi-view projection, and it will be a non-isometricline in an isometric projection or drawing of thesame object.The line AB appears in its true lengthin the top multi-view view because it is parallelto the plane of the view (the horizontal plane);but it will appear as a non-isometric line,and therefore not in its true length, in anisometric drawing, as shown in the bottompart of figure 5-40. It follows that you cannottransfer AB directly from the multi-viewprojection to the isometric drawing. You can,however, transfer directly all the normal lines inthe multi-view projection, which will be isometriclines appearing in their true lengths in theisometric drawing. When you have done this, youwill have constructed the entire isometric draw-ing, exclusive of line AB and of its counterparton the bottom face of the block. The end pointsof AB and of its counterpart will be located,however, and it will only be necessary to connectthem by straight lines.Angles in Isometric.In a normal multi-viewview of an object, an angle will appear in its truesize. In an isometric projection or drawing, anangle never appears in its true size, Even an angleformed by normal lines, such as each of the90-degree corner angles of the block shown in thebottom part of figure 5-41, appears distorted inisometric.The same principle used in transferringa non-isometric line is used to transfer anangle in isometric. The upperpart of figure 5-41shows a two-view multi-view projection of ablock. On the top face of the block, the lineAB makes a 40-degree angle with the frontedge. The line AB is an oblique (that is, notnormal) line, which will appear as a non-isometricline in the isometric drawing. You locate the endpoints of AB on the isometric drawing byFigure 5-41.-Drawing an angle in isometric.5-22